Personal long-term command cache

Linux

• TCP port check:

nc -zv HOST PORT

• Get only matching strings ( example: *.mydoma.in ) with grep -o:

grep -o '[^/]*\.mydoma\.in' myfile

• Get public IPv4 address:

dig -4 +short myip.opendns.com @resolver1.opendns.com

• Publish current directory via HTTP on port 8000:

python3 -m http.server 8000 &

• unix timestamp to normal date:

date -d @<unixtime>

• List of available SSL ciphers of example.com:

nmap --script ssl-enum-ciphers -p 443 www.example.com
# if available sslscan does the job as well:
sslscan example.com

• generate load; 1 CPU core to 100%:

yes > /dev/null &

• tcpdump capture traffic on specified port:

tcpdump -peni any -w /tmp/capture.pcap -s 0 host HOSTNAME port PORT

udpdump: add -A udp to above

• Remove duplicate lines from file in one step (without sorting it first):

awk ‘!seen[$0]++’ file

• Edit command line in $EDITOR:
  Ctrl-X Ctrl-E

• Import a repo's gpg key into a separate keyring:

sudo apt-key --keyring /etc/apt/trusted.gpg.d/mykeyring.gpg add /path/to/mykey.key

• ssh connection throug a jumphost. Will end up as root at host given as parameter

function jump () { ssh -o ServerAliveInterval=60 -J <jumphost name> $1 -t 'sudo -i; bash -l' }

git

• Cherry-picking a range of commits without actually committing them so that you can edit further and even squash them:

git cherry-pick -n abcd1234^..bcde2345

• Fancy trail-like commit track graph: aliased to gloga by git plugin by the way

git log --oneline --decorate --grap --all

• Compare a file content between branches:

git diff mybranch master -- where/is/the/file

• git config snippet for gpg signing commits:

[user]
	email = csaba[AT]lehoczki[.]me
	name = "Csaba Lehoczki"
	signingkey = AB4E2EC3812ACEE8
[commit]
	gpgsign = true

ZFS

• Remove all snapshots from a ZFS dataset:

zfs destroy -rvn dataset_or_zvol_name@%

remove -n if you really want to kill them

• Delete zfs snapshots matching a pattern:

zfs list -t snapshot -H -o name -r [parent dataset] | grep [pattern] | xargs -n1 echo

If you got what you want; substitute echo with zfs destroy

• zfs send/receive via SSH (one command only; slover but safer)

zfs send -R zpool/dataset/name@snapshot-to-send | ssh TARGET sudo zfs receive -Fu zpool/dataset/name

• zfs send/receive via netcat - plain bitstream instead of ssh tunnel (faster and less CPU intensive)

First start listener on target machine and pipe it to zfs receive:

nc -lp PORT | zfs receive zpool/dataset/name

Send snapshot stream recursively from the source machine:

zfs send -R zpool/dataset/name@snapshot-to-send | nc -w 20 TARGETHOST PORT

Windows CMD

• Force clean shutdown:

shutdown /s /f /t 0

• Force checkdisk on next reboot:

chkdsk C: /f /r /x

• System info:

systeminfo /FO csv > machine.csv
gpresult.exe /F /H machine.html

Windows PowerShell

• Enable ps1 file execution:

Set-ExecutionPolicy Bypass -Scope Process -Force

• Telnet client:

$tcp = New-Object System.Net.Sockets.TcpClient
$tcp.connect('<remote server>', <port>)

• wget:

Invoke-Webrequest -Uri <source> -OutFile <destination>

• grep: Select-String is the full name, abbrev sls:

sls pattern .\filename

OpenSSL

• Cert debug:

openssl s_server -accept PORT -cert ca.cert -key ca.key
openssl s_client -CAfile ca.cert -connect HOST:PORT
openssl s_client -host HOST -port PORT
openssl s_client -connect localhost:PORT

• Read pem(base64 format) cert:

openssl x509 -noout -text -in mycert.pem

• Read CSR:

openssl req -noout -text -in mycsr.csr

• Generate new CSR and key:

openssl req -nodes -new -newkey  rsa:2048 -out mycsr.csr -keyout mykey.key

• Generate new CSR from existing key:

openssl req -nodes -new -key my_existing.key -out mynewcsr.csr

• Generate new CSR from existing certificate and Key:

openssl x509 -x509toreq -in my_existing.crt -signkey my_existing.key -out mynew.csr

• Verify a cert matches a private key:

openssl x509 -noout -modulus -in mycert.crt
openssl rsa -noout -modulus -in mykey.key

• Fingerprint a cert:

openssl x509 -fingerprint -noout -in mycert.crt [-sha1 -md5]

Misc

• regex to match xml tags and content:
  

<mytag>[\s\S]*?<\/mytag>